1. Field of the Invention
The present invention relates to a communication device and a method used in a wireless communication system, and more particularly, to a communication device and method of handling uplink transmission in a wireless communication system.
2. Description of the Prior Art
A user equipment (UE) has to transmit a scheduling request to a network for requesting uplink (UL) resource(s) and the network has to transmit a UL grant to the UE for assigning the UL resource(s), before the UE performs UL transmission. A latency of the UL transmission can be expected, because a plurality of operation need to be performed before the UL transmission being performed. The latency can be reduced by that the network transmits the UL grant to the UE periodically, such that the UE can perform the UL transmission via the UL resource (s) assigned in the UL grant whenever necessary.
According to the prior art, the UE has to perform the UL transmission once the UE receives the UL grant, even if the UE does not have UL data for transmission. Thus, a UL transmission skipping mechanism, which allows the UE skipping the UL transmission if the UE does not have the UL data for transmission, is proposed for improving power consumption of the UE. However, the network cannot distinguish a failed UL transmission from a skipped UL transmission, when the UL transmission skipping mechanism is operated by the UE. Thus, the network cannot decode the UL transmission properly. As a result, throughput of decoding and the benefit of the power saving of the UL transmission skipping mechanism are degraded.
Thus, how to handle the UL transmission performed with the UL transmission skipping mechanism is an important problem to be solved.